Embodiments of the invention relate to systems and methods for enhancing scanned images acquired or generated using a conventional scanner or a multifunction device (“MFD”) capable of any combination of scanning, faxing, copying, or printing functions.
Many scanning systems scan documents and create scanned images of the documents using a variety of processes. An exemplary process is an automatic background detection process that extracts background information from the document. The background information is used for a variety of purposes. For example, the scanning systems can use the automatic background detection process to determine pixel values of the scanned images of the document and to identify a pixel as background if the pixel value satisfies some pre-determined criteria. In other cases, the automatic background detection process determines the pixel values from pixels in a region such as a leading edge of the scanned images of the document.
After the background pixels have been identified, the scanning systems generally use other processes to categorize or analyze characteristics of the background and to alter the characteristics of the background. For example, scanning systems may generate histograms or frequency distribution charts based on the values of the background pixels and determine some statistics of the pixel values. The statistics can include a peak value, a medium value, a mean value, and a standard deviation. Using the histograms and the statistics, the scanning systems can identify or estimate an intensity level of the background and a gain factor that can be used to compensate for a background gray level of the document.